Hybrid electric vehicles or the like incorporate a semiconductor device in an inverter. For cooling the semiconductor device, a water-cooling heat exchanger is adopted. With respect to the inverter mounting the semiconductor device, higher output power has been desired while a reduction in size and weight also has been demanded increasingly. Accordingly, a demand for a heat exchanger superior to a heat dissipation effect has been increased. Patent Literature 1 listed below discloses a conventional heat exchanger having improved cooling capability. FIG. 10 is a sectional plan view of the heat exchanger disclosed in Patent Literature 1.
The heat exchanger 100 includes a plurality of fins 111 defining refrigerant passages in a case 101 formed with a supply port 102 and a discharge port 103. In particular, three fin groups; first, second and third fin groups 201, 202, and 203 are separately provided in a refrigerant flow direction (in a lateral direction in FIG. 10). Each of the fin groups 201, 202, and 203 includes a plurality of fins 111 arranged in a lateral orientation and in parallel with one another. Between the fin groups 201 to 203, merging sections 105 and 106 are formed.
In this heat exchanger 100, the refrigerant will flow from the supply port 102 to the discharge port 103 through straight passages defined by the fins 111, and multiple refrigerant flows join together at the merging sections 105 and 106 to equalize flow distribution and then will diverge into downstream passages. Meanwhile, in the case where the passages defined by the fins 111 are straight, the refrigerant tend to flow in laminar form, which does not easily dissipate the heat conducted through the fins 111, resulting in poor cooling capability. It is therefore conceivable to arrange the fins 111 of the fin groups 201 to 203 so that the fins 111 are offset between upstream and downstream sides in a refrigerant flow direction as shown in Patent Literature 2 for example, thereby causing the refrigerant to impinge on the fins 111 located on the downstream side to disturb the refrigerant flows.